Use of wind turbines for electrical energy generation is currently growing because of their economical power production and environmental benefits, and because of the growing realization that other sources of energy are limited. Large wind turbines, located in off shore or remote wind farms are increasingly being installed worldwide. They can produce megawatts of electric power with lower costs than many other types of power production, and they do not pollute.
Another application for wind turbines is in small wind turbines, typically of 10 kilowatts peak power or less. Such small wind turbines have been deployed on farms for providing some electricity production, but their use has generally been limited because of certain deficiencies. An additional emerging market opportunity for small wind turbines is in urban and suburban installations. In these installations, customers expect to be able to produce some of their own electric power and offset their utility bills through net metering. Urban and suburban wind turbines will be located where people live, with installations on rooftops, in yards and along roadsides. They will reduce electricity transmission losses and the need for additional transmission lines.
Unfortunately, small wind turbines currently suffer from substantial deficiencies that limit their use and are preventing their widespread adoption. Small wind turbines are currently much too expensive for the energy that they produce. They have less than ideal energy capture, conversion and efficiency. They typically employ complex and costly constructions. Most small wind turbines are also noisy and require the use of towers that are unsightly and difficult to zone and install, both limiting their suitability for urban and suburban installations. Other deficiencies include rotor turbulence sensitivity, overspeed structural failure potential and avian-unfriendliness. Accordingly, a new type of small wind turbine system is needed.